The following are descriptions for the half-life of a radioactive mineral:

- "is carbon 14."

- "how many times you divide it in half to see how many times it took
you to get the original number; you then multiply it by the years."

- "is when the elements parent breaks down; the daughter then is given
part of his life - the older the element is, the higher the daughter's
half life is."

- "is the amount of time it takes for one half of the nucleus to dissolve."

- "when radioisotope known as the parent ears down and decays throughout
millions of years, it causes the isotopes to become the daughter, which
weakens radioisotopes as years go on."

- "the time that half the nucleus has decyaed.

- "parent isotope decrease half its life, and the daughter isotope increases
to half its life."

- "have [sic] life is how much radioactive will heave the element after
a period of time; a way of us calculating how old a rock is."

- "is the amount of time it takes the radioactivce element to half evaporate."

- "it means when an element is found in a rock of a certain number of
years, it means the element could have been around twice as long as the
age of the rock."

- "to divide every whole in half, starting from the top going."

- "the life of the radioisotope which is the amount of isotope times
half of the atomic number."

- "the middle of the element in process is which helps form the element
itself."

- "when an element only has certain chemically compounded minerals when
test [sic] and not fully formed."

- "half-life of radioactivity would represent if a rock were 2 times
older than another rock, it would have half of its radioactivity level."

- "take the life ofan elent and divide it by 2 in order to reach the
desired atomic weight, and see how many half-lives has the element been.

- "it is half of the every one million years."

NOVEL THEORIES OF DINOSAUR EXTINCTION

Over the years, there has never been a shortage of dinosaur extinction
theories, ranging from the very elegant and simple to the very complex
and bizarre. Here are some novel theories (written by students on exams)
that you may not have heard of:

"Dinosaurs became instinct [sic] because the Earth's atmosphere was
changing and dinosaurs could not adapt to it."

"They became instinct [sic] because cavemen ate them for supper."

"There weren't enough dinosaurs to reproduce more dinosaurs."

"The dinosaurs were too clumsy and too big to move around and were too
slow to survive on the land."

"The dinosaurs ate poisonous plants that were on the land and existed
the same time as the dinosaurs did."

"The dinosaurs and other animals ate the unborn dinosaur eggs, and reproduction
became extinct."

"Some believe the dinosaurs became sterile and could no longer reproduce."

"They were fuzzy eaters ."

"They ate poisonous plants."

"They were stupid."

"They ate everything."

"They were very picky eaters."

"They got mad easily."

One of the recently proposed dinosaur extinction theories involves
comets from the Oort Cloud (located at the edge of the solar system) striking
the earth 65 million years ago. The following answers were written by students
as criticisms of the Oort Cloud theory as a viable explanation for dinosaur
extinction:

"Whenever the sun passes threw [sic] the Mickey [sic] Way plane, they
suggest the swirls of dust, it encounters would graviationally [sic] disrupt
the Oobit [sic] Cloud - 10.0 trillion miles from the sun."

"The sun is very close to the glasic [sic] plane and still it is not
caused an extensions [sic] for millions of years."